Codeforces Round #703 (Div. 2)D（二分，前綴和）

https://codeforces.com/contest/1486/problem/D

 1 #define IO std::ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
 2 #define bug(x) cout<<#x<<" is "<<x<<endl
 3 #include <bits/stdc++.h>
 4 #define iter ::iterator
 5 using namespace  std;
 6 typedef long long ll;
 7 typedef pair<int,ll>P;
 8 #define pb push_back
 9 #define mk make_pair
10 #define se second
11 #define fi first
12 #define rs o*2+1
13 #define ls o*2
14 const ll inf=1e18;
15 const int N=2e5+5;
16 int T,n,k;
17 
18 int a[N],b[N],c[N];
19 
20 int check(int x){
21     for(int i=1;i<=n;i++){
22         if(a[i]<x)b[i]=b[i-1]-1;
23         else b[i]=b[i-1]+1;
24         c[i]=min(c[i-1],b[i]);
25     }
26     int f=0;
27     for(int i=k;i<=n;i++){
28         if(b[i]-c[i-k]>0){
29             f=1;
30             break;
31         }
32     }
33     return f;
34 }
35 int main(){
36     IO;
37     cin>>n>>k;
38     for(int i=1;i<=n;i++){
39         cin>>a[i];
40     }
41     int l=1,r=n+1;
42     while(r-l>1){
43         int m=(l+r)/2;
44         if(check(m))l=m;
45         else r=m;
46     }
47     cout<<l<<endl;
48 }